The Central Bureau of Investigation (CBI) on Monday obtained judicial permission to conduct a polygraph test on Sanjoy Roy, the prime accused in the RG Kar Medical College rape and murder case, sources said. The Central agency may also petition the court to conduct a similar test on Sandip Ghosh, the former principal of the college, who, according to agency sources, is “not fully cooperating” with the investigation.

Roy, who was initially arrested by the Kolkata Police and later handed over to the CBI following a Calcutta High Court order, is the only accused arrested so far.

According to sources, CBI officials have found that Roy, a civic volunteer attached to the Kolkata Police, visited RGKMCH three times on the evening and night before August 9, when the body of the postgraduate lady doctor was discovered in a semi-nude condition.

Roy first visited the hospital’s surgery department at 6 pm to see a patient. He returned at 11 pm and proceeded directly to the seminar hall of the Department of Chest Medicine on the 3rd floor. Sources said he visited the same location again around 4 am the following morning, staying inside for about 30-35 minutes — the estimated time when the crime was committed, according to autopsy reports.

A postgraduate trainee doctor was raped and murdered at the RG Kar Medical College and Hospital in Kolkata while on duty last week leading to nationwide and even international protests demanding security for doctors.

A polygraph test, commonly known as a lie detector test, measures physiological responses such as blood pressure, heart rate, and other indicators while the accused is asked a series of questions.

The aim is to determine whether the individual is telling the truth based on these responses. However, the accuracy of polygraph tests is often debated by experts.

The Agency on Monday petitioned the Sealdah Court for Roy’s polygraph test as he was providing misleading answers to certain queries as to why despite being an outsider he visited the chest medicine department at 11 pm or for that matter why he returned at 4 am the next morning.

According to inside sources the CBI is also planning a polygraph test for Ghosh who too h ad been providing evasive answers. Ghosh has already been interrogated for about 50 hours in four days but has provided “misleading and contradictory answers … or often has either kept mum or refused to reply to questions.”

According to sources the orthopedic surgeon who allegedly enjoys a considerable clout in the State administrative circles --- having managed to thwart or get his transfer orders reversed thrice --- has not made it clear as to under whose instructions the parents of the victim was told that she had committed suicide or for that matter why they were not allowed to see and inspect the her body for more than three hours after they reached the medical college.

The former principal has also not explained the reason behind demolition of the wall separating the seminar hall where the victim’s body was found and the adjacent room within hours of the recovery of the body neither has he provided answers to who instructed such demolition, sources said adding he also refused to share with his interrogators the names of the people he immediately contacted after getting the news of the victim’s death. He is known to have given some names but not all, sources said.

“If he cooperates then well and good or else he too could be put to polygraph test ... agency official are not ruling out that possibility,” an insider said.

Meanwhile, the doctors of Kolkata on Monday celebrated the Raksha Bandhan by tying black Rakhis on each other’s hands while thousands of doctors marched to Lal Bazaar police headquarters along with senior specialists Dr Kunal Sarkar and Dr Subarna Goswami who had earlier been summoned by the police for allegedly spreading disinformation on the social media.

The top doctors were however, released after sometime following discussions with the top officials, sources said. “We have told the police that if they want cooperation we are always there but if they summon us like this then we will always march to Lal Bazaar in protest because we have not done anything wrong by standing for the cause of humanity,” Dr Goswami said while Dr Sarkar asked the Government to “listen to the people’s voice ensure safety and security not only for the women doctors but all the women at their work places.”

Elsewhere the lawyers too joined the protest on Monday while a large swarm of Calcutta High Court lawyers including senior barristers hitting the streets expressing solidarity for the doctors’ movement.